ConclusionsEther-soluble material giving a positive Zimmerman reaction is present in gastric juice in varying concentrations. Evidence is lacking of a direct correlation between acidity of the juice and concentration of the steroids. Concentration of 17-KS in gastric juice is shown to increase markedly during intravenous administration of hydrocortisone; hence it appears to reflect to some extent the blood level of hydrocortisone. The inference is justified that the gastric mucosa is the site of active steroid metabolism.